First example of isatin used in four-component synthesis of ionic unsymmetrical scaffold with three different heterocyclic rings

The new type of four-component tandem Knoevenagel–Michael reaction was found: isatins, barbituric acids, malononitrile and morpholine at ambient temperature and without catalysts selectively form new non-symmetrical ionic scaffold, namely, morpholin-4-ium 5-(3-dicyanomethyl-2-oxoindolin-3-yl)-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetra-hydropyrimidin-4-olate derivatives, in 80-98% yields. Their structure was confirmed using 2D NMR such as ¹H-¹H COSY, ¹H-¹³C HSQC, and ¹H-¹³C HMBC correlation experiments. The products seem promising as they contain three different pharmacologically active heterocyclic rings.